主要用于工业管道中蒸汽介质流体的流量测量,蒸汽涡街流量计特点是压力损失小,量程范围大,精度高,在测量工况体积流量时几乎不受流体密度、压力、温度、粘度等参数的影响。 The DEC-LU series gas vortex flowmeter is mainly used for the flow measurement of steam medium fluid in industrial pipelines. The characteristics of the steam vortex flowmeter are small pressure loss, large range and high accuracy. Influence of parameters such as fluid density, pressure, temperature, viscosity, etc. No moving mechanical parts, so high reliability and low maintenance. Instrument parameters can be stable for a long time. If a triangular cylindrical vortex generator is set in the steam fluid, regular vortices are alternately generated from both sides of the vortex generator. This vortex is called a Carmen vortex. As shown in the figure on the right, the vortex row is asymmetrically downstream of the vortex generator arrangement.
Suppose the frequency of vortex occurrence is f, the average flow velocity of the measured medium is, the width of the front surface of the vortex generator is d, and the diameter of the surface body is D, then the following relationship can be obtained:
f = SrU1 / d = SrU / md (1)
Where U1 is the average flow velocity on both sides of the vortex generator, m / s;
m－the ratio of the arcuate area on both sides of the vortex generator to the cross-sectional area of the pipe
qv = πD2U / 4 = πD2mdf / 4Sr (2)
K = f / qv = [πD2md / 4Sr] -1 (3)
In the formula, K is the meter coefficient of the flow meter, and the number of pulses / m3 (P / m3).
K is related not only to the geometry of the vortex generator and the pipeline, but also to the Strouhal number. The Strouhal number is a dimensionless parameter, which is related to the shape of the vortex generator and the Reynolds number. Figure 2 shows the relationship between the Strawhall number of the cylindrical vortex generator and the Reynolds number of the pipeline. It can be seen from the figure that in the range of ReD = 2 × 104 ～ 7 × 106, Sr can be regarded as a constant, which is the normal working range of the meter. When measuring the gas flow, the VSF flow calculation formula is (4)
Figure 2 The relationship between the Strouhal number and the Reynolds number, where qVn, qV are the volume flow under standard conditions (0oC or 20oC, 101.325kPa) and working conditions, m3 / h;
Pn, P-absolute pressures under standard conditions and working conditions, Pa;
Tn, T-the thermodynamic temperature under standard conditions and working conditions, K;
Zn, Z-the gas compression coefficients under standard conditions and working conditions, respectively.
It can be seen from the above formula that the pulse frequency signal output by VSF is not affected by the fluid physical properties and composition changes, that is, the meter coefficient is only related to the shape and size of the vortex generator and the pipeline within a certain Reynolds number range. But as a flow meter needs to detect the mass flow in the material balance and energy measurement, the output signal of the flow meter should monitor the volume flow and fluid density at the same time. The fluid properties and components have a direct impact on the flow measurement.
便是依据卡门旋涡原理进行封闭管道流体流量测量的新型流量计。 Gas vortex flowmeter is a new type of flowmeter for measuring fluid flow in closed pipes based on the Carmen vortex principle. Because of its good medium adaptability, it can directly measure the working volume flow of steam, air, gas, water, and liquid without temperature and pressure compensation. Equipped with temperature and pressure sensors, it can measure standard volume flow and mass flow, which is throttling. The ideal replacement for the flow meter.
In order to improve the high temperature resistance and vibration resistance of gas vortex flowmeters, our company has recently developed an improved SKLUG vortex flow sensor. Due to its unique structure and material selection, the sensor can ≤1g) Use under severe conditions.
In practical applications, the maximum flow rate is often much lower than the upper limit value of the meter. As the load changes, the minimum flow rate is often lower than the lower limit value of the meter. The meter is not working in its optimal working section. One problem is usually to reduce the diameter at the measurement site to increase the flow velocity at the measurement site, and choose a smaller diameter instrument to facilitate the measurement of the instrument, but this method of diameter reduction must have a straight length of 15D or more between the reducer and the instrument. Pipe sections are rectified, making processing and installation inconvenient. The LGZ variable diameter rectifier developed by our company has a circular arc shape. It has multiple functions of rectifying, increasing the flow rate and changing the flow rate distribution. Its structure size is small, only 1/3 of the inner diameter of the process tube. It is integrated with the vortex flowmeter. Not only does not need to add another straight pipe section, it can also reduce the requirements for the straight pipe section of the process pipe, and the installation is very convenient.
For the convenience of use, the battery-powered on-site display gas vortex flowmeter adopts micro power consumption high-tech. It can be operated for more than one year without interruption by using lithium battery. Flow, cumulative flow, etc. The temperature compensation integrated vortex flowmeter also has a temperature sensor, which can directly measure the temperature of the saturated steam and calculate the pressure, thereby displaying the mass flow of the saturated steam. Temperature and pressure compensation integrated type with temperature and pressure sensors for gas flow measurement can directly measure the temperature and pressure of the gas medium, thereby displaying the standard volume flow of the gas.
The gas vortex flowmeter uses a piezoelectric stress sensor with high reliability and can work in the operating temperature range of -20 ° C to + 250 ° C. It has analog standard signal and digital pulse signal output. It is easy to be used with digital systems such as computers. It is a relatively advanced and ideal flow meter.
Measurement medium: gas, liquid, vapour
◆ Flange connection caliber selection: 100, 150, 200
◆ Flow measurement range Normal measurement flow range Reynolds number 1.5 × 104 ～ 4 × 106; gas 5 ～ 50m / s; liquid 0.5 ～ 7m / s
Normal measurement flow range See Table 2 for liquid and gas flow measurement ranges; Table 3 for vapor flow range
◆ Measurement accuracy 1.0 grade 1.5 grade ◆ Temperature of measured medium: normal temperature -25 ℃ ～ 100 ℃
◆ High temperature-25 ℃ ～ 150 ℃ -25 ℃ ～ 250 ℃
◆ Output signal pulse voltage output signal high level 8 ～ 10V low level 0.7 ～ 1.3V
◆ Pulse duty is about 50%, transmission distance is 100m
◆ Pulse current remote transmission signal 4 ～ 20 mA, transmission distance is 1000m
◆ Using ambient temperature of the meter: -25 ℃ ～ + 55 ℃ Humidity: 5 ～ 90% RH50 ℃
◆ Material stainless steel, aluminum alloy ◆ Power source DC24V or lithium battery 3.6V
◆ Explosion-proof grade intrinsically safe iaIIbT3-T6 protection grade IP65
How to adjust the gas vortex flowmeter
主要用于工业管道介质流体的流量测量,如气体、液体、蒸气等多种介质。 Gas vortex flowmeters are mainly used to measure the flow of medium fluids in industrial pipelines, such as gases, liquids, vapors and other media. It is characterized by small pressure loss, large measuring range and high accuracy. It is hardly affected by parameters such as fluid density, pressure, temperature, and viscosity when measuring working volume flow. No moving mechanical parts, so high reliability and low maintenance. Instrument parameters can be stable for a long time. This instrument uses a piezoelectric stress sensor with high reliability and can work in the operating temperature range of -20 ℃ ～ + 250 ℃. It has analog standard signal and digital pulse signal output. It is easy to be used with digital systems such as computers. It is a relatively advanced and ideal flow meter. Then this article mainly introduces how to adjust the gas vortex flowmeter. How to adjust the gas vortex flowmeter-the main problems are: ① long-term inaccurate instructions; ② no instructions at all times; ③ large-scale fluctuations of instructions, unable to read; The indication does not return to zero; ⑤ No indication at small flows; 指示 The indication is OK at large flows; the indication is inaccurate at small flows; 指示 The indication changes cannot keep up when the flow changes; k The k-factor of the meter cannot be determined, and many data are inconsistent. How to adjust the gas vortex flowmeter-analysis and solution of the main problems: 1. Problems in selection. Some vortex sensors have been selected in a large size or after design and selection due to changes in process conditions, which made the selection larger—a specification. The actual selection should choose the smallest size possible to improve measurement accuracy. The main reasons for this are the same. Questions ①, ③, ⑥ are related. For example, a vortex street pipeline is designed to be used by several equipments. Because the process equipment is sometimes not used, the current actual flow rate is reduced. The actual use causes the original design to be selected too large, which is equivalent to increasing the measurable flow rate. Lower limit, the indication cannot be guaranteed when the flow rate of the process pipeline is small, and it can be used when the flow rate is large, because it is sometimes too difficult to rebuild. Changes in process conditions are only temporary. Can be combined with parameter re-tuning to improve the indication accuracy. 2. Installation problems. The main reason is that the length of the straight pipe section in front of the sensor is not enough, which affects the measurement accuracy. The reason for this is mainly related to problem ①. For example: The straight pipe section in front of the sensor is obviously insufficient. Since fic203 is not used for metering, it is only used for control, so the current accuracy can be used equivalent to degraded use. 3. Reason for parameter setting direction. Due to the parameter error, the meter indication is wrong. The parameter error causes the secondary meter full-scale frequency to be calculated incorrectly. The main reason for this is related to problems ① and ③. The full-scale frequency is similar, which makes the indication inaccurate for a long time. The full-scale frequency calculated by the actual full-scale frequency makes the indication fluctuate widely and cannot be read. The inconsistency of the parameters on the data affects the final determination of the parameters. Re-calibration combined with mutual comparison determined the parameters and solved this problem. 4. Secondary instrument failure. This part has many faults, including: once the instrument circuit board is disconnected, the range setting has individual bits displayed badly, the k coefficient setting has individual bits displayed badly, making it impossible to determine the range setting and the k coefficient setting. Part of the reason is mainly related to problems ① and ②. The problem was resolved by fixing the corresponding fault. 5, four-way line connection problems. Some circuits look good on the surface of the circuit. Carefully check that some connectors are actually loose and cause the circuit to be interrupted. Although some connectors are tightly connected, due to the problem of the auxiliary line, the fastening screws are fastened to the wire cover, which also makes the circuit. Interruption, this part of the cause is mainly related to problem ②.